The present invention relates to projectiles; and in particular to projectiles requiring a rotating band(s) to impact spin and to seal off propellant gases.
It is known to employ a rotating band on a projectile. The band can be made of a soft materials such as copper that can conform to the rifling in a gun tube, without excessively wearing the tube. When the gun is fired, high pressure gas is applied to the aft end of the projectile. As the projectile travels forward, the rotating band is squeezed into the rifling of the gun tube, so that the projectile is spun for dynamic stability during flight.
A disadvantage with known projectiles is the high cost associated with critical metals such as copper that are used in the rotating band. This expense is especially significant when the projectile is being used only for training. In the past, training has been limited due to this expense.
Also, known projectiles have had difficulty in sealing the projectiles to the gun tube so that high pressure gas drives the projectile without leaking past it. Again, the sealing devices have used critical materials which are relatively expensive.
Accordingly, there is a need for a relatively reliable and inexpensive device for engaging rifling on a gun tube, and for sealing high pressure gases so that a projectile can be fired accurately and can travel its full range.